local voucherId = ARGV[1]
local userId = ARGV[2]
local orderId = ARGV[3]

local stockKey = 'seckill:stock:' .. voucherId
local orderKey = 'seckill:order:' .. voucherId

-- 库存不足返回1
if (tonumber(redis.call("get", stockKey)) <= 0) then
    return 1
end
-- 用户已下单返回2
if (redis.call('sismember', orderKey, userId) == 1) then
    return 2
end

-- 扣库存、下单
redis.call('incrby', stockKey, -1)
redis.call('sadd', orderKey, userId)

--发送消息到队列中
redis.call('xadd', 'stream.orders', '*', 'userId', userId, 'voucherId', voucherId, 'id', orderId)
return 0